The urogenital area harbors a complex microbial ecosystem comprising more than 50 different bacterial species (Hill et al., Scand. J. Urol. Nephrol. 1984; 86 (suppl.) 23-29). The dominating species for fertile women in this area are lactic acid producing bacteria belonging to the genus Lactobacillus. These lactic acid producing members are important for retaining a healthy microbial flora in these areas, and act as probiotic bacteria with an antagonistic effect against pathogenic microbial species. Lactic acid producing bacteria inhibit growth and colonization by other microorganisms by occupying suitable niches for colonization, by forming biofilms and competing for available nutrients, thereby excluding colonization by harmful microorganisms. Also, the production of hydrogen peroxide, specific inhibiting substances, such as bacteriocines, and organic acids (including lactic acid and acetic acid) that lower the pH, inhibit colonization by other microorganisms.
The microbial ecosystem of a healthy individual can be disturbed by the use of antibiotics, during hormonal changes, such as during pregnancy or use of contraceptives with estrogen, during menstruation, after menopause, in people suffering from diabetes etc. Also, microorganisms may spread from the anus to the urogenital area, thereby causing infections. This results in a disturbance of the normal microbial flora and leaves the individual susceptible to microbial infections that cause vaginitis, urinary tract infections and ordinary skin infections. Microorganisms commonly associated with these kinds of infections belong to the genera Escherichia, Enterococcus, Psedomonas, Proteus, Klebsiella, Streptococcus, Staphylococcus, Gardnerella and Candida. Women are at particular risk due to their shorter distance between the anus and the urogenital tract; specially at risk are young women, who not yet have a well developed microflora in the urogenital area and older women, who no longer have a protective flora.
One way to reduce the problems with the kinds of infections described above is to have a good personal hygiene. However, excessive use of cleaning agents not only decrease the amount of harmful microbes, but can harm the beneficial microbial flora, again render it susceptible for pathogenic species to colonize and cause infections. Alternatively, administration of lactic acid producing bacteria to the urogenital area and the skin in order to outcompete pathogenic species and facilitate reestablishment and maintenance of a beneficial microbial flora in these areas, have been found to be a successful means to treat and prevent microbial infections.
It has been suggested that lactic acid producing bacteria can be delivered via absorbent products, such as diapers, sanitary napkin, incontinence guards, panty liners and tampons, as described in, for example, WO 92/13577, WO 97/02846, WO 99/17813, WO 99/45099 and WO 00/35502.
A major problem with providing products intended to be used for transfer of lactic acid producing bacteria, is that the bacteria have to retain viability during transport and storage of the products. A major problem with products comprising lactic acid producing bacteria is that the bacteria rapidly lose viability under semi-moist conditions, and it is therefore important that the products are not exposed to moisture.
With “semi-moist” conditions is meant that the water activity (aw) is between about 0.2 and about 0.9. Water activity aw measures the vapour pressure generated by the moisture present in a hygroscopic product.aw=p/ps,where:    p: partial pressure of water vapour at the surface of the product    ps: saturation pressure, or the partial pressure of water vapour above pure water at the product temperature
Water activity reflects the active part of moisture content or the part which, under normal circumstances, can be exchanged between the product and its environment.
Water activity is usually defined under static conditions of equilibrium. Under such conditions, the partial pressure of water vapour (p) at the surface of the product is equal to the partial pressure of water vapour in the immediate environment of the product. Any exchange of moisture between the product and its environment is driven by a difference between these two partial pressures.
One way to partly overcome this problem has been to supply products with freeze-dried lactic acid producing bacteria. However, if the bacteria in the products are not protected from moisture after manufacturing of the products, the air humidity will subsequently kill the bacteria and the shelf-life of such products will then be shortened. Another disadvantage with the direct application of dried lactic acid producing bacteria to a hygiene product, such as an absorbent product, is that transfer of the bacteria to the urogenital area will be low.
In order to overcome the problem with air humidity decreasing the shelf-life of products containing lactic acid producing bacteria it has been suggested to prepare dispersions of lactic acid producing bacteria and a hydrophobic substance, such as a fat or an oil. Research experiments have shown that storage in sterile vaseline oil results in a high level of viable lactobacilli cells after 8 months of storage (Arkadéva et al., N A. Nauchnye Doklady Vysshei Shkoly. Biologicheskie Nauki, 1983, 2:101-104). However, Stoianova et al. (Mikrobiologiia, 2000, 69:98-104), found that immersion in mineral oil was not effective to preserve viability of lactic acid producing bacteria. U.S. Pat. No. 4,518,696 describes liquid suspensions of Lactobacilli in sunflower oil for oral administration to animals. However, none of the above references are concerned with the problems associated with retaining a high viability of lactic acid producing bacteria on hygiene products to be used to administer lactic acid producing bacteria to the urogenital area of a subject.
There are additional examples of the combination lactic acid producing bacteria and an oil, although these do not describe the effect of the oil on the survival of the lactic acid producing bacteria. WO 01/13956 describes the use of pharmaceutical compositions comprising Emu oil, antimicrobial agents and/or Bacillus coagulans to be used for antimicrobial treatments. However, Bacillus coagulans is not naturally occurring in the normal human urogenital flora and is mainly used as odor inhibitor and is not adapted to improve the microbial flora in humans. Bacillus coagulans is forming spores and is therefore not sensitive for normal moisture. WO 02/28446 describes the use of an essentially hydrophobic carrier and freeze-dried lactic acid producing bacteria to prepare a distribution to be applied to an absorbent product. The hydrophobic carrier was mainly chosen to overcome problems with applying the bacteria to the absorbent product during manufacturing, but the carrier also protects the bacteria from air humidity.
In conclusion, there is still a need to develop products for delivery of lactic acid producing bacteria to the urogenital area that are convenient to use, result in efficient transfer of the bacteria to the area where they are applied and that can be stored for long time periods without loss of viability of the bacterial cells.